Foundations of sensation and
perception
General principles
Transduction: receptor cells convert environmental energy into electrical nerve
impulses. Receptors
Lesion: specific area of a brain is surgically removed or destroyed, to observe
the consequences.
Microelectrode recording: electrodes are inserted through the white of the
eye, activity is recorded in individual retinal ganglion cells. The cells are
specialized.
Computerized tomography: (CT) medical technique, X-rays are passed through
the body at different angles, the resulting data are processed to form a detailed
image of the body structure.
Magnetic resonance imaging: detect the magnetic properties of brain
molecules, by radio waves passing through the head in all directions. fMRI scans
inform about the brain function.
Psychophysics: scientific study of relationships between physical stimuli and
perceptual phenomena.
Computation: all sufficiently powerful computing devices are essentially
identical. Basis for artificial intelligence (AI).
Connectionism: simulate aspects of perception and cognition using large
networks of simple processing units that bear a superficial similarity to neurons.
Neural impulses: electrical signals that convey information from the nervous
system. They travel from a cell’s dendrites and body, to its terminal buttons,
typically via an axon. The terminal buttons connect to the dendrites of other cells
at synapses, when the impulse reaches did, there is a release of
neurotransmitter. Which can be excitatory (increasing the probability that the
neuron will generate an impulse) or inhibitory.
In all of the senses, expect olfaction, one of the synapses in located in the
thalamus. When the signals arrive at the receiving area in the cortex, they are
passed on to association areas.
Receptive field: limited spatial area of a cell’s response.
Specific nerve energy: neural signals in the senses are differentiated by their
pathways in the nervous system, rather than by differences in the nature of the
signals themselves.
Cortical magnification: the exaggerated cortical representation of one part of a
sensory dimension or surface compared to another.
Adaptability: vary its response characteristics to match prevailing stimulation.
Ion channel: a specialized protein molecule that allows certain ions to enter or
leave a cell.
Qualia = sensations: specific brain status.
Psychometric function: graph of the relation between stimulus level and the
probability of detection by an observers, shows a smooth transition between no-
detection and detection as stimulus level increases.
Magnitude estimation: establish the precise relationship between physical
stimulus magnitude and sensory magnitude.
, Stevens’s power law: sensory magnitude grows in proportion to stimulus
intensity raised to a power, equal ratios of intensity correspond to equal ratios of
sensory magnitude.
Adaptation: continuous exposure to a relatively intense stimulus. More intense
stimulus is required to induce a perceptual response, the apparent intensity of
the stimulus diminishes and the rate at which sensory magnitude increases with
stimulus level steepens.
Representations: specific internal state of the brain, in the form of a particular
pattern of neural activity in some sense represents the state of the outside world.
Analog (values in one system, vary proportionately with values in another
system) and symbolic (discrete symbols act as tokens for the state of another
system).
Population coding: character of shape is encoded by the pattern of activity
across the whole population of cells.
Labelled line: a specific neural pathway that is only active in the presence of its
triggering stimulus. Computation: manipulation of quantities or symbols
according to a set of formal rules. The formal rules are algorithms.
Linking proposition: a particular mapping occurs between perceptual and
physiological states.
Tutorial:
Absolute threshold: smallest amount of stimulus energy required for an
observer to just detect its presence.
Differential threshold: minimum change in stimulus energy that can be
detected by an observer (JND).
Classical psychophysical theory: there is an ideal threshold function that relates
the internal response to the stimulus level, it is a step function with two levels
(high/low), when the level is high and the stimulus is always detected.
Method of adjustment: a psychophysical procedure, the subject need to adjust
the value of a stimulus to estimate there threshold.
Method of constant stimuli: psychophysical procedure, preselected stimuli are
presented to the subject in random order and the subject makes a binary
response after each trial.
Signal detection theory (SDT): Subject’s decisions are determined jointly by
their sensory response and a response-tendency. In such a task only half of the
presentations contain stimuli (random), there can be a yes/no task or a forced-
choice task.
d’-prime: a measure of stimulus sensitivity based on DDT, represents the
increase in sensory response caused by the presence of stimulus.
Bias (β): extend to which the subject is predisposed towards making a particular
response, regardless of stimulus level.
Scientific theory: must provide a framework for organizing and understanding the
known facts in an economical manner, must attempt to provide explanations for
the facts/suggest causal links and must be capable of generating predictions that
can be tested. They can be compared with the empirical consistency (ability to
explain known facts), logical consistency/computability (judge their relative
merits on the basis of logical consistency), Occam’s Razor (not too much entities)
and generality (wider context, connections other theories).
perception
General principles
Transduction: receptor cells convert environmental energy into electrical nerve
impulses. Receptors
Lesion: specific area of a brain is surgically removed or destroyed, to observe
the consequences.
Microelectrode recording: electrodes are inserted through the white of the
eye, activity is recorded in individual retinal ganglion cells. The cells are
specialized.
Computerized tomography: (CT) medical technique, X-rays are passed through
the body at different angles, the resulting data are processed to form a detailed
image of the body structure.
Magnetic resonance imaging: detect the magnetic properties of brain
molecules, by radio waves passing through the head in all directions. fMRI scans
inform about the brain function.
Psychophysics: scientific study of relationships between physical stimuli and
perceptual phenomena.
Computation: all sufficiently powerful computing devices are essentially
identical. Basis for artificial intelligence (AI).
Connectionism: simulate aspects of perception and cognition using large
networks of simple processing units that bear a superficial similarity to neurons.
Neural impulses: electrical signals that convey information from the nervous
system. They travel from a cell’s dendrites and body, to its terminal buttons,
typically via an axon. The terminal buttons connect to the dendrites of other cells
at synapses, when the impulse reaches did, there is a release of
neurotransmitter. Which can be excitatory (increasing the probability that the
neuron will generate an impulse) or inhibitory.
In all of the senses, expect olfaction, one of the synapses in located in the
thalamus. When the signals arrive at the receiving area in the cortex, they are
passed on to association areas.
Receptive field: limited spatial area of a cell’s response.
Specific nerve energy: neural signals in the senses are differentiated by their
pathways in the nervous system, rather than by differences in the nature of the
signals themselves.
Cortical magnification: the exaggerated cortical representation of one part of a
sensory dimension or surface compared to another.
Adaptability: vary its response characteristics to match prevailing stimulation.
Ion channel: a specialized protein molecule that allows certain ions to enter or
leave a cell.
Qualia = sensations: specific brain status.
Psychometric function: graph of the relation between stimulus level and the
probability of detection by an observers, shows a smooth transition between no-
detection and detection as stimulus level increases.
Magnitude estimation: establish the precise relationship between physical
stimulus magnitude and sensory magnitude.
, Stevens’s power law: sensory magnitude grows in proportion to stimulus
intensity raised to a power, equal ratios of intensity correspond to equal ratios of
sensory magnitude.
Adaptation: continuous exposure to a relatively intense stimulus. More intense
stimulus is required to induce a perceptual response, the apparent intensity of
the stimulus diminishes and the rate at which sensory magnitude increases with
stimulus level steepens.
Representations: specific internal state of the brain, in the form of a particular
pattern of neural activity in some sense represents the state of the outside world.
Analog (values in one system, vary proportionately with values in another
system) and symbolic (discrete symbols act as tokens for the state of another
system).
Population coding: character of shape is encoded by the pattern of activity
across the whole population of cells.
Labelled line: a specific neural pathway that is only active in the presence of its
triggering stimulus. Computation: manipulation of quantities or symbols
according to a set of formal rules. The formal rules are algorithms.
Linking proposition: a particular mapping occurs between perceptual and
physiological states.
Tutorial:
Absolute threshold: smallest amount of stimulus energy required for an
observer to just detect its presence.
Differential threshold: minimum change in stimulus energy that can be
detected by an observer (JND).
Classical psychophysical theory: there is an ideal threshold function that relates
the internal response to the stimulus level, it is a step function with two levels
(high/low), when the level is high and the stimulus is always detected.
Method of adjustment: a psychophysical procedure, the subject need to adjust
the value of a stimulus to estimate there threshold.
Method of constant stimuli: psychophysical procedure, preselected stimuli are
presented to the subject in random order and the subject makes a binary
response after each trial.
Signal detection theory (SDT): Subject’s decisions are determined jointly by
their sensory response and a response-tendency. In such a task only half of the
presentations contain stimuli (random), there can be a yes/no task or a forced-
choice task.
d’-prime: a measure of stimulus sensitivity based on DDT, represents the
increase in sensory response caused by the presence of stimulus.
Bias (β): extend to which the subject is predisposed towards making a particular
response, regardless of stimulus level.
Scientific theory: must provide a framework for organizing and understanding the
known facts in an economical manner, must attempt to provide explanations for
the facts/suggest causal links and must be capable of generating predictions that
can be tested. They can be compared with the empirical consistency (ability to
explain known facts), logical consistency/computability (judge their relative
merits on the basis of logical consistency), Occam’s Razor (not too much entities)
and generality (wider context, connections other theories).
